Prevalence of Bartonella species and 16s rRNA gene types of Bartonella henselae from domestic cats in Thailand.

Prevalence of Bartonella infection among 275 cats in 9 sites from 4 geographical regions (northern area: Chiang Mai; central area: Kanchanaburi, Ratchaburi, and Bangkok; northeastern area: Khon Kaen, Roi Et, Ubon Ratcharthani, and Nakhonratchasima; southern area: Songkhla) of Thailand was investigated. Overall, Bartonella species were isolated from 27.6% (76 of 275) of the cats. The isolation rate varied from 12.8% (5 of 39) in Songkhla (southern area) to 50.0% (26 of 52) in Khon Kaen (northeastern area). Bartonella henselae and B. clarridgeiae were isolated from 82.9% (63 of 76) and 11.8% (9 of 76) of the Bartonella-positive cats, respectively. Coinfection with both species was found in 5.3% (4 of 76) of the bacteremic cats. Of the 67 bacteremic cats from which B. henselae was isolated, 48 (71.6%) and 13 (19.4%) were infected with only Type I and Type II, respectively. Coinfection with both types was observed in 9.0% (6 of 67) of the B. henselae-positive cats. To our knowledge, this is the first report on the presence of Bartonella infection in domestic cats from Thailand, which constitute a large reservoir of Bartonella infection in this country.

Seroprevalence of Bartonella henselae and Toxoplasma gondii among healthy individuals in Thailand.

The seroprevalence of Bartonella henselae and Toxoplasma gondii among apparently healthy individuals, mainly blood donors, in Thailand was investigated by an indirect fluorescent antibody technique and by a latex agglutination test, respectively. Of 163 serum samples examined, 9 (5.5%) were found to be positive for B. henselae-IgG, 2 (1.2%) for B. henselae-IgM, and 5 (3.1%) for the T. gondii antibody. No significant difference was observed between male and female samples in the serological test with either B. henselae or T. gondii. The age of individuals with B. henselae-IgG was distributed from the 20s to the 70s, and B. henselae-IgM was found in the individuals of the 30s and 60s. The age of T. gondii positive samples ranged from the 20s to the 60s. In this study, the prevalence of B. henselae infection among healthy individuals in Thailand was serologically demonstrated for the first time.

Salmonella in broiler chickens in Thailand with special reference to contamination of retail meat with Salmonella enteritidis.

The present study was performed to assess the prevalence of Salmonella in chickens in Thailand. In 1997, 22 serovars of Salmonella were isolated from 72 of 100 chicken meat samples purchased from 10 retail markets in Bangkok and 20 of 200 chicken meat samples from one slaughterhouse for export and 19 of 285 chicken feces obtained from three farms located in the east region of Thailand. The most predominant serovar was S. Enteritidis, which was isolated from 28% of the retail chicken meat, 4.5% of the chicken meat from slaughterhouse, and 6.6% of chickens feces samples examined.

Predominant serovars of Salmonella in humans and foods from Thailand.

During the period from 1993 to 1996, a total of 27,497 Salmonella isolates from humans, chicken meat, ready-to-eat Thai foods and shrimps were serotyped to know the predominant serovars of Salmonella in humans and foods in Thailand. Seventy-two and 81 serovars of Salmonella were identified in human and food samples, respectively. The significance of foods as a vehicle for human salmonellosis was discussed from an epidemiological viewpoint.

Significant increase in antibiotic resistance of Salmonella isolates from human beings and chicken meat in Thailand.

A total of 1715 Salmonella strains, including 600 S. enteritidis, 290 S.derby, 257 S. Weltevreden, 122 S. 1,4,5,12:i:-, 235 S. anatum, and 211 S. typhimurium, originating from 1308 human beings and 407 frozen chicken meat specimens collected in 1993 and 1994 were tested for antibiotic resistance. The disk diffusion method was used with nine disks of chloramphenicol, ceftriaxone, amikacin, kanamycin, ampicillin, sulfamethoxazole plus trimethoprim, nalidixic acid, gentamicin and ofloxacin. The resistance rates of human beings isolates in 1994 to ceftriaxone, amikacin and kanamycin were, respectively, 10.7%, 8.6%, 17.8% in S. enteritidis; 23.1%, 17.3% 33.0% in S. derby; 30.9%, 40.2%, 60.4% in S. weltevreden; 16.1%, 17.7%, 70.9% in S.1, 4, 5, 12:i:-; 25.7%, 21.6%, 24.7% in S. anatum; 18.9%, 15.7%, 37.8% in S. typhimurium, while those isolates in 1993 to the same three antibiotics were, respectively, 1.8%, 0.6%, 3.7% in S. enteritidis; 0.8%, 0%, 9.1% in S.derby; 1.8%, 2.7%, 10.8% in S. weltevreden; 3.8%, 0%, 23.0% in S.1, 4, 5, 12:i:-; 2.2%, 2.2%, 6.7% in S. anatum; 4.5%, 1.5%, 10.6% in S. typhimurium. It was shown that the resistance rates in 1994 were significantly higher than those in 1993. All isolates were susceptible to ofloxacin with the exception of one isolate.

Epidemiological analysis of Salmonella enteritidis isolates from humans and broiler chickens in Thailand by phage typing and pulsed-field gel electrophoresis.

To determine the phage types (PT) of Salmonella enteritidis found in Thailand and to clarify the potential for human infection by S. enteritidis in broiler chicken meat, human and poultry isolates taken from Thailand between 1990 and 1997 were phage typed and analyzed by pulsed-field gel electrophoresis (PFGE). Ten different PT were found among the 302 isolates phage typed, with PT 4 being the most frequent in human (73.9%) and poultry (76.2%) isolates, followed by PT 1 (8.0%), 8 (3.6%), and 7a (2.2%) in human isolates and by PT 7a (4.9%), 1 (3.7%), and 12 (2.4%) in poultry isolates. Of the 53 isolates analyzed by PFGE, 45 showed an indistinguishable pattern (pattern A) by BlnI-digested PFGE and the other 8 isolates showed a very similar pattern that differed by only a few bands. These results indicate the spread of a genetically identical clone of S. enteritidis in humans and poultry in Thailand.

Risk factors for hepatitis C virus infection among blood donors in an HIV-epidemic area in Thailand.

OBJECTIVE: The role of sexual transmission in hepatitis C virus (HCV) infection has not yet been completely elucidated. This study aimed to compare the risk factors for HCV and human immunodeficiency virus (HIV) infection in an HIV epidemic area of Thailand where HIV is mainly transmitted heterosexually. DESIGN AND SUBJECTS: Sera from 3053 blood donors were collected and tested for HCV and HIV between January and March 1994. Altogether 1756 (57.5%) of the donors were interviewed about demographics and several risk factors. RESULTS: The prevalence rates of HIV and HCV infections determined by antibody assays were 2.3% and 2.2%, respectively. Sexual risk factors were clearly shown among anti-HIV positive donors. These clear associations were not found, however, among anti-HCV positive donors. In contrast, previous histories of injecting drug use and being tattooed were found in some anti-HCV positive donors but less frequently in anti-HIV positive donors. CONCLUSIONS: Sexual transmission may play a relatively minor role in HCV transmission compared with HIV, in this area.

The putative nucleocapsid and envelope protein genes of hepatitis C virus determined by comparison of the nucleotide sequences of two isolates derived from an experimentally infected chimpanzee and healthy human carriers.

cDNA fragments of a 5'-terminal region of the hepatitis C virus (HCV) genome were isolated by the reverse polymerase chain reaction from RNA extracted from plasma samples of healthy Japanese carriers. Their nucleotide sequence was compared with that of the original isolate which had been passaged twice in chimpanzees. No deletions or insertions were observed between the two sequences in the regions examined. Both the 5' untranslated and putative nucleocapsid (core) protein regions were highly conserved (99% and 91% nucleotide identities, respectively). In contrast, the region immediately downstream which encodes a putative envelope glycoprotein(s) showed only 74% nucleotide identity between the two isolates. At the polypeptide level, the core and envelope domains showed 97% and 75% amino acid identities, respectively. This envelope variation may reflect the adaptation of HCV to the different hosts and/or the result of immunological selection. The highly conserved nucleotide sequence of the 5' untranslated and core regions may play an important regulatory role in the life cycle of HCV.

Hepatitis C viral cDNA clones isolated from a healthy carrier donor implicated in post-transfusion non-A, non-B hepatitis.

Using a specific hepatitis C virus (HCV) antibody assay, positive blood donors responsible for the transmission of post-transfusion non-A, non-B hepatitis (PT-NANBH) were identified. cDNA fragments were isolated from one of the plasma samples of such healthy HCV carriers by using polymerase chain reactions. Nucleotide (nt) sequence analyses of the cDNA from three different regions of the viral genome revealed that they were derived from a Japanese HCV isolate that was similar but not identical to the prototype HCV previously isolated from a chronically infected chimpanzee. Homology at the nt and amino acid levels was comparatively lower in the presumed structural region than in putative nonstructural regions. This result not only confirms that HCV antibody-positive blood contains infectious HCV, but suggests the existence of different type(s) of HCV.

Prevalence of hepatitis C virus antibody among healthy blood donors and non-A, non-B hepatitis patients in Thailand.

With the antigen expressed in yeast from a cDNA clone encoding a non-structural region of newly discovered hepatitic C virus (HCV) genome, the prevalence of HCV antibody in people in Thailand was investigated. Antibody was detected in 2.6% of healthy blood donors and in 2.8% of healthy pregnant women. These prevalence rates were higher than those reported previously from Japan, USA and European countries. Among community-acquired, sporadic cases of acute and chronic non-A, non-B hepatitis, however, only 5.7% and 15.4% were shown to possess the antibody, respectively. Among hepatocellular carcinoma patients who were negative for hepatitis B surface antigen in the sera, 11.1% had antibody to HCV. These seroepidemiological data suggest that HCV plays an important role as an etiological agent in Thailand; however, other agents must also be involved in etiologic agents of viral hepatitis and chronic liver disease.

A cDNA fragment of hepatitis C virus isolated from an implicated donor of post-transfusion non-A, non-B hepatitis in Japan.

Recently, a cDNA from the hepatitis C virus (HCV) RNA genome has been isolated in the USA from a chronically infected chimpanzee. In order to isolate HCV cDNA derived from human material, RNA was extracted from plasma of a Japanese blood donor implicated in post-transfusion non-A, non-B hepatitis and HCV cDNA was synthesized and amplified by the PCR method using HCV-specific oligonucleotide primers. The cDNA fragment, 583 nucleotides long, showed 79.8% homology at the nucleotide level and 92.2% homology at the amino acid level compared with the prototype HCV cDNA. These results provides further evidence to show that HCV is closely associated with the development of post transfusion non-A, non-B hepatitis.

Protective efficacy of plasma-derived hepatitis beta vaccine in preventing perinatal transmission of HBV infection in infants of HBsAg/HBeAg positive mothers.

Two hundred and four newborn infants of HBsAg/HBeAg carrier mothers were randomly assigned into three groups. Group A (69 infants) received full-dose HB vaccine, group B (70 infants) received half-dose HB vaccine at birth, 1 month, 3 months and group C (65 infants) were untreated control group. After twelve months follow-up the cumulative incidence of HBs antigenemia was 17.2%, 30% in group A, B respectively as compared with 78.4% in group C (p less than 0.001). The protective efficacy rates (PER) of group A and B were 78.1% and 61.7% respectively (p less than 0.05). The vaccine was also effective in preventing persistent HBsAg carriers (HBsAg positive for at least 6 months). The PER of group A and B were at least 74.9% and 49.2% respectively (p less than 0.001) at 1 year follow-up. From the practical point of view and economic reasons administration of full-dose HB vaccine give better protection to high risk infants.